Polymer mixtures with optimized toughness/stiffness ratio and optical properties

ABSTRACT

The invention relates to a polymer mixture made of styrene/nitrile monomer copolymers and of graft copolymers based on acrylate rubbers, and also to thermoplastic moulding compositions and mouldings produced therefrom and use of these.

The invention relates to a polymer mixture of styrene/nitrile-monomercopolymers and of graft copolymers based on acrylate rubbers, and alsoto thermoplastic molding compositions produced therefrom, and moldings,and use of these.

Impact-resistant thermoplastic compositions are often obtained by addinggraft rubbers to the polymers that form the matrix, these being brittleat room temperature. The production of these impact modifiers has beenknown for a long time and is described by way of example in DEA 1260135,DEA 2311129, and DE-A 2826925. If the matrix is composed of polystyreneor of styrene copolymers, the effectiveness of the graft copolymers inrespect of their impact-modifying action can be seen to increase as thesize of the graft copolymers increases. Another problem with use ofsmall-particle graft rubbers is that the toughness of theimpact-modifying compositions is greatly dependent on the processingtemperature.

Polymeric compositions which have improved impact resistance and retainthe same good colorability can be obtained by adding a large-particlerubber component to a small-particle rubber component (bimodal rubberparticles), as described in DE-A 2826925. The impact resistance, inparticular the low-temperature impact resistance, achieved in thosecompositions is frequently inadequate for high stress levels. There aremoreover restrictions on the quantity of the large-particle rubber thatcan be added in order to increase impact resistance; if theserestrictions are ignored colorability is markedly impaired.

It is known that the properties of the soft acrylate phase can beimproved if the soft polymeric phase comprises at least one crosslinkingagent. U.S. Pat. No. 4,876,313 describes what are known as “core-shell”polymers obtainable via emulsion polymerization, comprising variouscrosslinking agents. Alkyl (meth)acrylates or styrene are preferablyused as “core monomer”, and methyl methacrylate and methacrylic acid arepreferably used as “shell monomer”. Among the preferred crosslinkingagents is allyl (meth)acrylate in a quantity of from 1 to 10% by weight,based on the “core monomer”. The core-shell polymers can be mixed withother multistage acrylic emulsions.

It is known that impact-resistant multiphase emulsion polymers of theASA (acrylonitrile-styrene-acrylate) type have a particularly balancedproperty profile when the soft acrylate phase comprises at least onecrosslinking agent.

EP-A 0535456 describes a thermoplastic molding composition with improvedimpact resistance comprising a styrene/acrylonitrile copolymer and amultishell graft copolymer, the core and the first graft shell of whichhave been crosslinked with from 0.1 to 10% by weight, preferably from 1to 4% by weight, of a crosslinking agent, in particulardicyclopentadienyl acrylate. By way of example, graft copolymers aredescribed in which the crosslinked core is made of polystyrene, thefirst crosslinked shell is made of butyl acrylate, the second shell ismade of styrene, and the third shell is made of styrene andacrylonitrile.

DE-A 4006643 describes a thermoplastic molding composition made of astyrene/acrylonitrile copolymer or of an α-methylstyrene-acrylonitrilecopolymer, and of a particulate graft copolymer. The graft base is acrosslinked acrylate rubber with particle size from 30 to 1000 nm. Anumber of polyethylenically unsaturated monomers are listed ascrosslinking agents, including allyl methacrylate. Preferredcrosslinking agent, and the only crosslinking agent used, is the acrylicester of tricyclodecenyl alcohol (DCPA). The quantity of thecrosslinking agent is from 0.1 to 5% by weight, preferably from 1 to 4%by weight. The graft shell is preferably made of from 45 to 80% byweight of styrene or α-methylstyrene and from 10 to 30% by weight ofacrylonitrile.

The prior art cited shows that the materials can comprise variousquantities of the crosslinking agents. Application of the crosslinkerquantities mentioned in the prior art to ASA molding compositions withmarkedly different particle sizes is frequently successful only withsignificant losses of impact resistance. The relationship between theideal quantities of crosslinking agents in impact-modified ASA moldingcompositions and the particle size thereof is not clear.

DE-A 2826925 describes a weathering-resistant, impact-resistantthermoplastic composition with good colorability, composed of a graftcopolymer along with a hard component made of styrene/acrylonitrilecopolymers.

The graft copolymer is composed of two graft copolymers producedseparately, each of which is composed of a crosslinked acrylate graftbase and of a shell made of acrylonitrile/styrene copolymers, where theparticle size of the graft base of the first graft copolymer is from 50to 150 nm and that of the second graft copolymer is from 200 to 500 nm.Preferred crosslinking agent, and the only crosslinking agent used, isthe acrylic ester of tricyclodecenyl alcohol. The quantity of thecrosslinking agent is from 0.5 to 10% by weight, preferably from 1 to 5%by weight.

DE-A 4131729 describes a thermoplastic molding composition with improvedlow-temperature toughness made of a styrene/acrylonitrile copolymer orof an α-methylstyrene-acrylonitrile copolymer and of a mixture ofparticulate graft copolymers A and B with particle size from 50 to 200nm and from 200 to 1000 nm. The graft bases A1 and B1 are variouscrosslinked acrylate rubbers. A number of polyethylenically unsaturatedmonomers are listed as crosslinking agents. Preferred crosslinkingagent, and the only crosslinking agent used, is the acrylic ester oftricyclodecenyl alcohol (DCPA). The quantity of the crosslinking agentis from 0.1 to 5% by weight, preferably from 0.2 to 4% by weight, forexample 2% by weight. The graft shell is preferably made of from 45 to80% by weight of styrene or α-methylstyrene and from 10 to 30% by weightof acrylonitrile.

EP-A 1 893 659 likewise describes molding compositions based on ASAresins with an elastomeric phase and a thermoplastic phase. Theelastomeric phase is a rubber substrate based on an alkyl (meth)acrylatemonomer and on at least one crosslinking agent. Many polyethylenicallyunsaturated monomers are listed as crosslinking agents. Preferredcrosslinking agent, and the only crosslinking agent used, is triallylcyanurate. A portion of the thermoplastic hard phase, which preferablycomprises a styrene/acrylonitrile copolymer or astyrene/acrylonitrile/methyl methacrylate copolymer, has been graftedonto the elastomeric rubber phase. The elastomeric phase can comprisetwo or more rubber substrates with various particle sizes in the rangefrom 50 to 1000 nm (measured ungrafted), in particular in the range from80 to 500 nm. One embodiment uses an excess of the rubber substratehaving relatively fine particles.

The abovementioned molding compositions have improved gloss and reducedhaze, but mechanical properties, in particular at low temperatures,still require improvement. It is an object of the present invention toprovide thermoplastic compositions which especially at low temperaturesbelow 0° C., preferably irrespective of the processing temperature, havebetter impact resistance and stress-cracking-corrosion behavior, and inparticular better multiaxial toughness values. The gloss of the moldingcomposition should moreover be improved or at least maintained.

The object is achieved via the polymer mixtures of the invention.

The invention provides polymer mixtures made of the following polymercomponents A1 and A2, and/or A3, Polymer mixtures provided are thereforethose made of polymer components A1 and A2, those made of polymercomponents A1 and A3, and also those made of polymer components A1 andA2 and A3, and in particular the following quantity ranges can be usedhere:

A1: from 5 to 95% by weight of a copolymer A1 of:

A11: from 60 to 80% by weight of at least one styrene or styrenederivative A11,

A12: from 40 to 20% by weight of at least one ethylenically unsaturatedmonomer A12 comprising a nitrile group,

A13: from 0 to 20% by weight of at least one other, copolymerizablemonomer A13;

A2: from 5 to 50% by weight of a graft copolymer A2 with median particlesize from 90 to 280 nm, of:

A21: from 60 to 80% by weight of at least one rubber-like graft base A21with Tg<0° C. made of

A211: from 70 to 99.9% by weight of at least one alkyl (meth)acrylateA211,

A212: from 0.2 to 0.8% by weight of at least one allyl (meth)acrylateA212,

A213: from 0 to 2% by weight of at least one other monomer A213 havingat least 2 unconjugated ethylenic double bonds,

A214: from 0 to 29.9% by weight of at least one other copolymerizablemonomer A214,

A22: from 20 to 40% by weight of at least one graft shell made of:

A221: from 65 to 70% by weight of at least one vinylaromatic monomerA221,

A222: from 30 to 35% by weight of at least one polar, copolymerizableunsaturated monomer A222,

A223: from 0 to 30% by weight of at least one other, copolymerizablemonomer A223; and/or

A3: from 5-50% by weight of a graft copolymer A3 with particle size from300 to 600 nm, of:

A31: from 60 to 80% by weight of at least one rubber-like graft base A31with Tg<0° C. made of

A311: from 70 to 99.9% by weight of at least one alkyl (meth)acrylateA311,

A312: from 0.1 to 0.5% by weight of at least one allyl (meth)acrylateA312

A313: from 0 to 2% by weight of at least one other monomer A313 havingat least 2 unconjugated ethylenic double bonds,

A314: from 0 to 29.9% by weight of at least one other copolymerizablemonomer A314,

A32: from 20 to 40% by weight of at least one graft shell made of:

A321: from 65 to 70% by weight of at least one vinylaromatic monomerA321,

A322: from 30 to 35% by weight of at least one polar, copolymerizableunsaturated monomer A322,

A323: from 0 to 30% by weight of at least one other, copolymerizablemonomer A323.

The ratio by weight of component A2 to component A3 is often from 3:1 to1:1. The proportions by weight of polymer components A1, A2, and/or A3are intended to give a total of 100% by weight.

The respective ratios by weight in the polymer mixtures are often by wayof example:

-   -   a) of A1 and A2 from 65:35 to 75:25, often 70:30,    -   b) of A1 and A3 from 65:35 to 75:25, often 70:30, and    -   c) of A1, A2, and A3 about 70:20:10.

The expression (meth)acrylate monomers means methacrylate monomers andacrylate monomers.

The polymer mixtures of the invention can also comprise auxiliariesand/or additives in addition to polymer components A1, A2, and/or A3.Preference is given to mixtures of the invention composed of from 50 to99.9% by weight, preferably from 70 to 99.9% by weight, of componentsA1, A2, and/or A3, and from 0.1 to 50% by weight, preferably from 0.1 to30% by weight, of the auxiliaries and/or additives.

Preference is further given to those polymer mixtures which comprisepolymer components A1, A2, and A3.

Component A1

Quantities used of component A1 are from 5 to 95% by weight, preferablyfrom 10 to 90% by weight, in particular from 30 to 80% by weight, veryparticularly preferably from 50 to 80% by weight.

Suitable monomers A11 are styrene and styrene derivatives such asα-methylstyrene and ring-alkylated styrenes, for example p-methylstyreneand/or tert-butylstyrene. Preference is given to styrene,α-methylstyrene, and/or p-methylstyrene, in particular styrene and/orα-methylstyrene, and very particular preference is given to use ofstyrene.

Monomers A12 used are preferably acrylonitrile and/or methacrylonitrile.Acrylonitrile is particularly preferred.

The proportion of the monomer A11 in the copolymer A1 is generally from60 to 80% by weight, preferably from 60 to 65% by weight.

The proportion of the monomer A12 in the copolymer A1 is generally from40 to 20% by weight, preferably from 40 to 35% by weight.

The copolymer A1 can moreover also comprise up to 20% by weight of atleast one other, copolymerizable monomer A13, for example methylacrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethylmethacrylate, phenylmaleimide, maleic anhydride, acrylamide, and/orvinyl methyl ether.

Preferred copolymers A1 are copolymers of styrene and acrylonitrileand/or copolymers of α-methylstyrene and acrylonitrile. It isparticularly preferable that A1 is a copolymer of styrene andacrylonitrile.

A1 can be produced by well-known methods (DE-A 31 49 358, p. 9, lines 18to 32 and DE-A 32 27 555, p. 9, lines 18 to 32), for example bywell-known copolymerization of A11, A12, and optionally A13 in bulk,solution, suspension, or aqueous emulsion at conventional temperaturesand pressures in known apparatuses (reference Kunststoff-Handbuch[Plastics handbook], Vieweg-Daumiller, volume V (Polystyrol[Polystyrene]), Carl-Hanser-Verlag, Munich 1969, p. 124, lines 12 ff.).

Component A2

Monomers A211 that can be used for the production of the rubber-likegraft base A21 are generally alkyl (meth)acrylates having astraight-chain or branched alkyl moiety having from 1 to 12 carbonatoms, preferably from 2 to 8 carbon atoms, particularly preferably from4 to 8 carbon atoms. Preference is given to alkyl acrylates having astraight-chain or branched alkyl moiety having from 1 to 12 carbonatoms, preferably from 2 to 8 carbon atoms, particularly preferably from4 to 8 carbon atoms, in particular n-butyl acrylate and/or ethylhexylacrylate. Production of the graft base A21 can use the alkyl(meth)acrylates individually or in a mixture.

The rubber-like graft base A21 also comprises from 0.2 to 0.8% byweight, preferably from 0.2 to 0.6% by weight, in particular from 0.4 to0.5% by weight, of at least one allyl (meth)acrylate A212 as monomercomponent. Allyl methacrylate is preferred.

A212 acts as crosslinking agent. The expression crosslinking agentsmeans at least bifunctional monomers having at least two reactive,unsaturated groups.

The rubber-like graft base A21 can moreover comprise up to 2% by weight,preferably up to 1% by weight, and in particular up to 0.5% by weight,of other copolymerizable monomers A213 having at least 2 ethylenicdouble bonds which are not conjugated in 1,3-position and which likewisefunction as crosslinking agent. Examples of suitable monomers A213 aredivinylbenzene, diallyl maleate, diallyl fumarate, and/or diallylphthalate, triallyl cyanurate, and preferably the acrylic ester oftricyclodecenyl acrylate (=dicyclopentadienyl acrylate (DCPA)).

It is preferable that the graft base A21 comprises no crosslinking agentA213.

Examples of possible other copolymerizable monomers A214 that can beused are the following compounds: alpha-methylstyrene,methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate,methyl methacrylate, ethyl methacrylate, phenylmaleimide, acrylamide,vinyl methyl ether. It is preferable that the graft base A21 comprisesno monomer A214.

Monomers A221 suitable for the production of the graft shell A22 arevinylaromatic monomers such as styrene and/or styrene derivatives, forexample alkylstyrene, preferably α-methylstyrene, and ring-alkylatedstyrenes, for example p-methylstyrene and/or tert-butylstyrene.

Preference is given to styrene and/or α-methylstyrene, particularlystyrene.

Examples of polar copolymerizable unsaturated monomers A222 areacrylonitrile and/or methacrylonitrile, preferably acrylonitrile.

Examples of possible other copolymerizable monomers A223 that can beused are the following compounds: acrylic acid, methacrylic acid, maleicanhydride, methyl acrylate, ethyl acrylate, propyl acrylate, methylmethacrylate, ethyl methacrylate, phenylmaleimide, acrylamide, and vinylmethyl ether. It is preferable that A223 is methyl methacrylate and/ormaleic anhydride.

It is preferable that the graft shell A22 is a copolymer of styreneand/or α-methylstyrene and acrylonitrile, preferably of styrene andacrylonitrile.

Component A3

Monomers A311, A312, A313 and A314 used for the graft base A31 are thecorresponding compounds described above for the graft base A21 (A211,A212, A213, and A214).

However, the quantity used of monomer component A312, i.e. allyl(meth)acrylate, is from 0.1 to 0.5% by weight, preferably from 0.1 to0.4% by weight, in particular from 0.1 to 0.2% by weight.

Monomers A321, A322 and A323 used for the graft shell A32 are likewisethe corresponding compounds described above for the graft shell A22(A221, A222 and A223).

In one preferred embodiment the polymer mixture of the invention made ofpolymer components A1 and A2 and/or A3 comprises:

A1: from 5 to 95% by weight of a copolymer A1 of

A11: from 60 to 80% by weight of styrene or α-methylstyrene A11,

A12: from 40 to 20% by weight of acrylonitrile A12,

A2: from 5 to 50% by weight of a graft copolymer A2 with median particlesize from 90 to 280 nm, of

A21: from 60 to 80% by weight of a rubber-like graft base A21 with Tg<0°C. made of

A211: from 70 to 99.9% by weight of at least one alkyl acrylate havingfrom 1 to 8 carbon atoms in the alkyl moiety A211,

A212: from 0.2 to 0.8% by weight of allyl methacrylate A212,

A22: from 20 to 40% by weight of at least one graft shell made of:

A221: from 65 to 70% by weight of styrene or α-methylstyrene A221,

A222: from 30 to 35% by weight of acrylonitrile A222, and/or

A3: from 5-50% by weight of a graft copolymer A3 with particle size from300 to 600 nm, of

A31: from 60 to 80% by weight of at least one rubber-like graft base A31with Tg<0° C. made of

A311: from 70 to 99.9% by weight of at least one alkyl acrylate havingfrom 1 to 8 carbon atoms in the alkyl moiety A311,

A312: from 0.1 to 0.5% by weight of allyl methacrylate A312,

A32: from 20 to 40% by weight of at least one graft shell made of:

A321: from 65 to 70% by weight of styrene or α-methylstyrene A321,

A322: from 30 to 35% by weight of acrylonitrile A322,

where the ratio by weight of component A2 to component A3 (if both arepresent) is from 3:1 to 1:1, and the proportions by weight of polymercomponents A1, A2, and/or A3 give a total of 100% by weight.

Preference is further given to polymer mixtures of the inventioncomprising components A1, A2, and A3 which comprise a quantity of from0.2 to 0.6% by weight, in particular from 0.4 to 0.5% by weight, of A212and from 0.1 to 0.4% by weight, in particular from 0.1 to 0.2% byweight, of A312.

The production of graft copolymers made of an elastomeric rubber-likegraft base and of a graft shell is well known (see by way of example DE4006643 A1, p. 2, line 65 to p. 3, line 43; DE 4131729 A1 p. 3, line 12to p. 4, line 49).

Fine-particle graft copolymers can be produced by way of example asdescribed in DE 4006643 A1 (p. 2, line 65 to p. 3, line 43).

Coarse-particle graft copolymers can be produced via grafting in twostages as described in DE 3227555 A1 (component B: p. 8, line 14 to p.10, line 5) and DE-A 31 49 358 (p. 8, line 14 to p. 10, line 5).

Production of the graft copolymers A2 generally begins with production,for example by emulsion polymerization, of the rubber-like acrylatepolymer A21 serving as graft base, in that by way of example alkylacrylate A211 and the crosslinking agent A212, and optionally A213and/or A214 are polymerized in aqueous emulsion in a manner known per seat temperatures of from 20 to 100° C., preferably from 50 to 80° C. Onthis resultant polyacrylate latex it is possible to graft a mixture ofvinylaromatic monomers A221 with a polar copolymerizable unsaturatedmonomer A222 and also optionally other monomers A223, and this graftcopolymerization is preferably likewise carried out in aqueous emulsion.

The production of the graft copolymers A3 proceeds, for the graft baseA31, as described above for A2, but the grafting usually proceeds in twostages where the vinylaromatic monomer A321 is generally firstpolymerized in the presence of the graft base A31. The graftcopolymerization with a mixture comprising at least one vinylaromaticmonomer A321 and at least one polar copolymerizable monomer A322, andalso optionally A323, can then be carried out in the second stage.

The quantities of the various components used and comprised in thepolymer mixture of the invention have already been described in theintroduction.

The polymerization process can moreover use the conventional auxiliariesand/or additives, for example emulsifiers, such as alkali metal salts ofalkyl- or alkylarylsulfonic acids, alkyl sulfates, fatty alcoholsulfonates, salts of higher fatty acids having from 10 to 30 carbonatoms, or resin soaps, polymerization initiators, for exampleconventional persulfates such as potassium persulfate, or known redoxsystems, polymerization auxiliaries, for example conventional buffersubstances that can be used for adjustment to pHs that are preferablyfrom 6 to 9, e.g. sodium bicarbonate and/or sodium pyrophosphate, and/ormolecular-weight regulators, for example mercaptans, terpinols, and/ordimeric α-methylstyrene, where the usual quantity used of themolecular-weight regulators is from 0 to 3% by weight, based on theweight of the reaction mixture.

The polymer mixture of the invention is produced by incorporating theparticulate graft polymers A2 and/or A3 described above into the hardcomponent, i.e. the copolymer A1. The method of incorporation can by wayof example be that the particulate graft polymer is isolated from theemulsion by adding an electrolyte and then, optionally after drying, ismixed with the hard component by extruding, kneading, or roll-millingthe materials together. The auxiliaries and/or additives below can alsobe added during the production of this mixture.

The material can comprise by way of example the following as auxiliariesand/or additives: plasticizers, antistatic agents, light stabilizers,lubricants, blowing agents, adhesion promoters, and optionally othercompatible thermoplastics, fillers, surface-active substances, flameretardants, dyes and pigments, stabilizers with respect to oxidation,hydrolysis, light, heat, or discoloration, and/or reinforcing agents.

Light stabilizers used can be any of the conventional light stabilizers,for example compounds based on benzophenone, on benzotriazole, oncinnamic acid, on organic phosphites and phosphonites; other examplesare sterically hindered amines.

Examples of lubricants are hydrocarbons such as oils, paraffins, PEwaxes, PP waxes, fatty alcohols having from 6 to 20 carbon atoms,ketones, carboxylic acids such as fatty acids, montanic acid, oroxidized PE wax, carboxamides, and also carboxylic esters, e.g. with thealcohols ethanol, fatty alcohols, glycerol, ethanediol, pentaerythritol,and long-chain carboxylic acids as acid component.

Stabilizers used can be conventional antioxidants, for example phenolicantioxidants, e.g. alkylated monophenols, esters and/or amides ofβ-(3,5-di-tert-butyl-4-hydroxy-phenylpropionic acid, and/orbenzotriazoles. Possible antioxidants are mentioned by way of example inEP-A 698637 and EP-A 669367. Specifically, mention may be made of thefollowing as phenolic antioxidants: 2,6-di-tert-butyl-4-methylphenol,pentaerythrityltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], andN,N′-di(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamine.The stabilizers mentioned can be used individually or in mixtures.

Other compatible thermoplastics can by way of example be polyesters(e.g. polyethylene terephthalate, polybutylene terephthalate), PMMA,polycarbonate, polyamide, polyoxymethylene, polystyrene, polyethylene,polypropylene, polyvinyl chloride.

These auxiliaries and/or additives can either be used before productionof thermoplastic component A1 concludes or else added to component A1,A2, and/or A3 during the production of the mixture.

The invention further provides moldings produced from the polymermixtures of the invention.

The polymer mixtures of the invention can by way of example bepelletized or granulated, or processed by well-known processes, forexample by extrusion, injection molding, blow molding, or calendering togive moldings of any type, for example cable sheathing, foils, hoses,fibers, profiles, shoe shells, shoe soles, technical moldings, consumeritems, coatings, bellows, and/or ear tags for animals.

A feature of the polymer mixtures of the invention, in particular at lowtemperatures in the range from 0 to −30° C., is an optimizedtoughness/stiffness ratio with retention of gloss.

The polymer mixtures of the invention can therefore be used particularlyadvantageously for the production of moldings that are used in thelow-temperature range from 0 to −30° C. By way of example, without anyrestriction thereto, mention may be made in this connection of outdoorapplications, e.g. in the automobile or construction sector.

The invention provides the production of the polymer mixtures via mixingof the components.

The invention therefore further provides the use, for outdoorapplications, of moldings produced from the polymer mixtures of theinvention.

The polymer mixtures and applications of the invention are described inmore detail with reference to the examples and claims below.

Examples

The parameters described in the present application were determined asfollows:

Notched impact resistance and impact resistance (kJ/m²): measured inaccordance with DIN 53 453 (ISO 179 1eA) on injection-molded standardsmall specimens at 23, 0, and −30° C., and with an injection-moldingtemperature of 220° C. In each case, three series of samples weretested. Tables 3-5 collate the results.

Median particle size is determined by using an ultracentrifuge and themethod of W. Scholtan and H. Lange, Kolloid-Z. and Z. Polymere 250(1972), 782-796. The ultrafuge measurement gives the cumulative massdistribution of the particles of a sample. The median particle diameterd50 is defined as follows: the diameter of 50% by weight of particles issmaller than, and the diameter of 50% by weight of the particles isgreater than, the d50 value.

Puncture is determined in accordance with ISO 6603-2/40/20/c.

Gloss is measured at 60° in accordance with DIN 67530.

Modulus of elasticity is determined in accordance with ISO 527-2:1993.

MVR (220/10) is determined in accordance with ISO 1133.

Component A1: Copolymer produced with 67% by weight of styrene as A11and 33% by weight of acrylonitrile as A12, IV; intrinsic viscosity(measured in 0.5% toluene solution at room temperature): 80 ml/g.

Component A1 was produced by a solution polymerization process asdescribed by way of example in: Kunststoff-Handbuch [Plastics handbook],ed. Vieweg-Daumiller, volume V (Polystyrol [Polystyrene]),Carl-Hanser-Verlag, Munich, 1969, p. 124, line 12 ff.

Component A2 Production of the Graft Base

The respective graft base was produced in accordance with the followinggeneral specification: 160 g of the monomer mixture stated in table 1were heated, with stirring, to 60° C. in 1500 g of water with additionof 5 g of sodium salt of a C₁₂- to C₁₈-paraffinsulfonic acid, 3 g ofpotassium peroxodisulfate, 3 g of sodium hydrogen-carbonate, and 1.5 gof sodium pyrophosphate. 10 minutes after the start of thepolymerization reaction, a further 840 g of the monomer mixture of table1 were added within a period of 3 hours. Once monomer addition hadended, the emulsion was kept at 60° C. for a further hour.

Production of the Particulate Graft Polymers

2100 g of the emulsion produced in accordance with specification (1)were mixed with 1150 g of water and 2.7 g of potassium peroxodisulfate,and heated, with stirring, to 65° C. Once the reaction temperature hadbeen reached, a mixture of 420 g of styrene (S) and 140 g ofacrylonitrile (AN) was metered into the mixture over the course of 3hours. Once addition was complete, the emulsion was kept at 65° C. for afurther 2 hours. The graft polymer was precipitated from the emulsion bymeans of calcium chloride solution at 95° C., washed with water, anddried in a stream of warm air.

Various graft copolymers A2 were produced with from 0.1 to 1.0% byweight of allyl methacrylate (AMA) as crosslinking agent. The medianparticle size of the resultant graft copolymer A2 was from 95-105 nm.Comparative examples CE1 and CE2 were also carried out, using DCPA (asin DE 4006643 A1, p. 5, table) instead of AMA.

TABLE 1 Monomer composition of graft copolymer A2 Graft base DCPA AMAGraft shell (% by DCPA (% by AMA (% by weight) BA weight) (mol) weight)(mol) S AN CE1 99.0 1.0 0.176 — — 75 25 CE2 98.0 2.0 0.352 — — 75 25A2-1 99.9 — — 0.1 0.029 75 25 A2-2 99.6 — — 0.4 0.116 75 25 A2-3 99.0 —— 1.0 0.290 75 25 Values in mol are based on 9.0 kg of mixture

Component A3 Production of the Graft Base A31

The quantitative data below for BA and AMA are based in each case onexamples A3-1/A3-2/A3-3 as in table 2.

16.31/16.26/16.21 parts of butyl acrylate (BA) and 0.02/0.08/0.15 partsof allyl methacrylate (AMA) are heated, with stirring, to 60° C. in 150parts of water with addition of one part of the sodium salt of aC₁₂-C₁₈-paraffinsulfonic acid, 0.3 part of potassium persulfate, 0.3part of sodium hydrogencarbonate and 0.15 part of sodium phosphate. 10minutes after the start of the polymerization reaction, a mixture of83.59/83.34/83.04 parts by weight of butyl acrylate and 0.08/0.32/0.60part of allyl methacrylate were added within a period of 3 hours. Oncemonomer addition had concluded, reaction of the mixture was allowed tocontinue for a further hour. The solids content of the resultant latexof the crosslinked butyl acrylate polymer was 40% by weight. Medianparticle size (weight average) was determined as 83/78/80 nm. Theparticle size distribution was narrow (quotient Q=0.20).

Production of a Coarse-Particle Graft Copolymer A3

The following were added to an initial charge made of 1.5 parts of thelatex A31 described above: after addition of 50 parts of water and 0.1part of potassium persulfate, over the course of 3 hours, at 60° C.,firstly a mixture made of 49.95/49.80/49.625 parts of butyl acrylate and0.05/0.20/0.375 part of allyl methacrylate, and secondly a solution of0.5 part of the sodium salt of a C₁₂-C₁₈-paraffinsulfonic acid in 25parts of water. Once the feed had ended, polymerization was continuedfor a further 2 hours. The solids content of the resultant latex of thecrosslinked butyl acrylate polymer was 40% by weight. Median particlesize (weight average of the latex) was determined as 473/459/460 nm.

The particle size distribution was narrow (quotient Q=0.15).

150 parts of this latex were then mixed with 20 parts of styrene and 60parts of water, and heated, with stirring, to 65° C. for 3 hours afteraddition of a further 0.03 part of potassium persulfate and 0.05 part oflauroyl peroxide. The dispersion obtained in the graft copolymerizationreaction was then polymerized for a further 4 hours with 20 parts of amixture of styrene and acrylonitrile in a ratio of 75:25. The reactionproduct was then precipitated from the dispersion with a calciumchloride solution at 95° C., isolated, washed with water, and dried in astream of warm air. The degree of grafting of the graft copolymer wasdetermined as 40%; the median size of the latex particles was564/545/551 nm.

Various graft copolymers A3 were produced with from 0.1 to 0.75% byweight of allyl methacrylate as crosslinking agent (table 2).

Comparative examples CE3 and CE4 were also carried out with DCPA (as inDE 4131729 A1, p. 6, table 1) instead of AMA.

TABLE 2 Monomer composition of graft copolymer A3 Graft base DCPA AMAGraft shell (% by DCPA (% by AMA (% by weight) BA weight) (mol) weight)(mol) S AN CE3 99.0 1.0 0.176 — — 75 25 CE4 98.0 2.0 0.352 — — 75 25A3-1 99.9 — — 0.1 0.029 75 25 A3-2 99.6 — — 0.4 0.116 75 25 A3-3 99.0 —— 0.75 0.217 75 25 Values in mol are based on 9.0 kg of mixture

The mixtures A1 and A2 (table 3), A1 and A3 (table 4), and A1, A2, andA3 (table 5) of the invention were produced by mixing the respectivecomponents intimately in an extruder (ZSK 30 twin-screw extruder fromWerner & Pfleiderer) at a temperature of 230° C. The respective ratiosby weight were 70:30 in the case of the mixture of A1 and A2, 70:30 inthe case of the mixture of A1 and A3, and 70:20:10 in the case of themixture of A1, A2, and A3.

The mixtures for the comparative examples using DCPA as crosslinkingagent component were likewise produced as described above.

The resultant mixtures were tested for various mechanical properties andfor gloss. Tables 3 to 5 collate the results.

TABLE 3 Polymer mixture of A1 and A2 Crosslinking agent Notched impactresistance Impact resistance Gloss (% by weight) 23° C. 0° C. −30° C.23° C. 0° C. −30° C. (60°) CE1 2.0% (0.353 mol) 8.0 6.4 2.5 — 248 100 93DCPA CE2 1.0% (0.176 mol) 5.9 5.4 2.5 — 240 119 88 DCPA 1 0.1% (0.029mol) 3.5 3.2 2.2 129 165 83 88 AMA 2 0.16% (0.046 mol) 5.4 5.2 2.5 179191 103 91 AMA 3 0.25% (0.0725 mol) 10.9 8.6 4.1 185 132 92 97 AMA 40.4% (0.116 mol) 12.0 10.4 4.6 233 199 139 97 AMA 5 0.5% (0.145 mol) 9.37.8 2.7 252 141 83 97 AMA 6 0.75% (0.217 mol) 9.1 6.6 2.1 177 133 67 96AMA 7 1 .0% (0.290 mol) 6.4 5.0 1.4 188 123 41 97 AMA Values in mol arebased on 9.0 kg of mixture CE1, CE2: comparative example using DCPAinstead of AMA

The polymer mixtures of the invention as in table 3, made of A1 and A2,show that a considerable improvement of notched impact resistance and ofimpact resistance at low temperatures, in particular at −30° C., isachieved by using a graft copolymer A2 comprising allyl methacrylate(AMA) A212, even when quantities of allyl methacrylate are small, i.e.from 0.1 to 0.5% by weight, while gloss is actually increased.

Corresponding comparative examples CE1 and CE2 using DCPA ascrosslinking component of the graft copolymer already show a glossreduction when the proportion of DCPA is reduced from 2 to 1% by weight.When quantities of DCPA used are from 0.2 to 0.8% by weight thecorresponding ASA product exhibits markedly matt surfaces, which are notdesired.

TABLE 4 Polymer mixture of A1 and A3 Crosslinking agent Notched impactresistance Impact resistance Gloss (% by weight) 23° C. 0° C. −30° C.23° C. 0° C. −30° C. (60°) CE3 2.0% (0.353 mol) 11.8 8.8 3.4 185 143 9599 DCPA CE4 1.0% (0.176 mol) 11.8 8.7 3.4 198 147 120 98 DCPA 1 0.1%(0.029 mol) 12.8 11.5 5.0 182 130 90 99 AMA 2 0.16% (0.046 mol) 12.5 9.95.0 — 171 124 99 AMA 3 0.2% (0.058 mol) 12.5 10.3 5.1 — 154 114 99 AMA 40.4% (0.116 mol) 12.1 9.3 5.0 — 218 132 100 AMA 5 0.5% (0.145 mol) 11.29.0 4.8 — 228 118 99 AMA 6 0.75% (0.217 mol) 9.6 8.4 4.7 — 178 126 99AMA Values in mol are based on 9.0 kg of mixture CE3, CE4: comparativeexamples

The polymer mixtures of the invention as in table 4, made of A1 and A3,show that a considerable improvement of notched impact resistance andimpact resistance at low temperatures, for example at −30° C., isachieved by using a coarse-particle graft copolymer A3 which comprisesonly small quantities of allyl methacrylate (AMA) A312 (from 0.1 to 0.5%by weight), while gloss is maintained. The mechanical properties of thepolymer mixtures of the invention are actually mostly better than whenmarkedly greater quantities of DCPA are used, while gloss is maintained.

These results were not expected and are surprising to the person skilledin the art, since it is general knowledge in the art that increasingcontent of crosslinking agent achieves increased or improved gloss (cf.,for example, U.S. Pat. No. 6,476,128). In contrast to this, acorresponding ASA product exhibits markedly matt surfaces when DCPA isused at a concentration in the range below 1% by weight.

TABLE 5 Polymer mixture of A1, A2 and A3 Notched impact Impactresistance Ak resistance Modulus of Penetration [kJ/m²] An [kJ/m²]elasticity MVR [kJ/m²] A2, A3 23° C. 0° C. −30° C. 23° C. 0° C. −30° C.[MPa] (220/10) 23° C. −20° C. CE1 2.0% by weight 8.9 7.4 2.7 — 144 932434 7.4 28.3 6.6 (0.353 mol) DCPA 2 0.16% by weight 10.9 8.2 3.6 — 153110 2455 8.0 39.8 12.8 (0.046 mol) AMA 3 0.4% by weight 10.5 6.5 2.0 —159 105 — 8.1 — — (0.115 mol) AMA 4 A2: 0.4% by weight 12.2 7.0 2.1 —181 101 — 8.3 — — (0.115 mol) AMA A3: 0.2% by weight (0.0575 mol) AMAValues in mol are based on 9.0 kg of mixture

The stated quantities of crosslinking agent were used mutuallyindependently respectively for component A2 and A3. The comparativeexample was carried out correspondingly, but using 2% by weight of DCPAinstead of AMA.

The polymer mixtures of the invention as in table 5, made of A1, A2, andA3, show that a considerable improvement of notched impact resistanceand impact resistance at temperatures including low temperatures isachieved by using the graft copolymers A2 and A3 respectively comprisingonly small quantities of allyl methacrylate.

Corresponding comparative examples as in the prior art using DCPA ascrosslinking component lead to markedly poorer results, althoughquantities of DCPA used were greater, namely respectively 2% by weightfor the coarse- and fine-particle graft copolymer.

From the polymer mixtures described it is possible, by using familiarmethods, to produce moldings which are in particular suitable forapplications including outdoor applications and which have an improvedtoughness/stiffness ratio and good optical properties.

1-10. (canceled)
 11. A polymer mixture of polymer components A1 and A2and/or A3: A1: from 5 to 95% by weight of a copolymer A1 of A11: from 60to 80% by weight of at least one styrene or styrene derivative A11, A12:from 40 to 20% by weight of at least one ethylenically unsaturatedmonomer A12 comprising a nitrile group, A13: from 0 to 20% by weight ofat least one other, copolymerizable monomer A13; A2: from 5 to 50% byweight of a graft copolymer A2 with median particle size from 90 to 280nm, of: A21: from 60 to 80% by weight of at least one rubber-like graftbase A21 with Tg<0° C. made of A211: from 70 to 99.9% by weight of atleast one alkyl acrylate A211, A212: from 0.1 to 0.6% by weight of atleast one allyl methacrylate A212, A214: from 0 to 29.9% by weight of atleast one other of the following copolymerizable monomers A214 selectedfrom methyl methacrylate, ethyl methacrylate, phenylmaleimide,acrylamide, and vinyl methyl ether, A22: from 20 to 40% by weight of atleast one graft shell made of: A221: from 65 to 70% by weight of atleast one vinylaromatic monomer A221, A222: from 30 to 35% by weight ofat least one polar, copolymerizable unsaturated monomer A222; and/or A3:from 5-50% by weight of a graft copolymer A3 with particle size from 300to 600 nm, of: A31: from 60 to 80% by weight of at least one rubber-likegraft base A31 with Tg<0° C. made of: A311: from 70 to 99.9% by weightof at least one alkyl acrylate A311, A312: from 0.1 to 0.4% by weight ofat least one allyl methacrylate A312, A314: from 0 to 29.9% by weight ofat least one other of the following copolymerizable monomers A314selected from methyl methacrylate, ethyl methacrylate, phenylmaleimide,acrylamide, and vinyl methyl ether, A32: from 20 to 40% by weight of atleast one graft shell made of: A321: from 65 to 70% by weight of atleast one vinylaromatic monomer A321, A322: from 30 to 35% by weight ofat least one polar, copolymerizable unsaturated monomer A322, where theproportions by weight of polymer components A1, A2, and/or A3 give atotal of 100% by weight.
 12. The polymer mixture as claimed in claim 11,characterized in that it also comprises auxiliaries and/or additives.13. The polymer mixture as claimed in claim 11, characterized in thatthe vinylaromatic monomer A221 and A321 is styrene, α-methylstyrene or amixture thereof.
 14. The polymer mixture as claimed in claim 11,characterized in that the polar monomer A222 and A322 is acrylonitrile,methacrylonitrile or a mixture thereof.
 15. The polymer mixture asclaimed in claim 11, comprising: A1: from 5 to 95% by weight of acopolymer A1 of A11: from 60 to 80% by weight of styrene orα-methylstyrene A11, A12: from 40 to 20% by weight of acrylonitrile A12,A2: from 5 to 50% by weight of a graft copolymer A2 with median particlesize from 90 to 280 nm, of A21: from 60 to 80% by weight of arubber-like graft base A21 with Tg<0° C. made of A211: at most 99.9% byweight of at least one alkyl acrylate having from 1 to 8 carbon atoms inthe alkyl moiety A211, A212: from 0.1 to 0.6% by weight of allylmethacrylate A212, A22: from 20 to 40% by weight of at least one graftshell made of: A221: from 65 to 70% by weight of styrene orα-methylstyrene A221, A222: from 30 to 35% by weight of acrylonitrileA222, and/or A3: from 5-50% by weight of a graft copolymer A3 withparticle size from 300 to 600 nm, of A31: from 60 to 80% by weight of atleast one rubber-like graft base A31 with Tg<0° C. made of A311: at most99.9% by weight of at least one alkyl acrylate having from 1 to 8 carbonatoms in the alkyl moiety A311, A312: from 0.1 to 0.5% by weight ofallyl methacrylate A312 A32: from 20 to 40% by weight of at least onegraft shell made of: A321: from 65 to 70% by weight of styrene orα-methylstyrene A321, A322: from 30 to 35% by weight of acrylonitrileA322, where the ratio by weight of component A2 to component A3 (if bothare present) is from 3:1 to 1:1, and the proportions by weight ofpolymer components A1, A2, and/or A3 give a total of 100% by weight. 16.The polymer mixture of polymer components A1, A2, and A3 as claimed inclaim 11, characterized in that: from 0.4 to 0.5% by weight of allylmethacrylate A212 and from 0.1 to 0.2% by weight of allyl methacrylateA312 are used.
 17. A molding produced from a polymer mixture as claimedin claim
 11. 18. A method of using moldings as claimed in claim 17 foroutdoor applications.
 19. A process for the production of the polymermixtures as claimed in claim 11, by mixing polymer components A1and A2,and/or A3, and optionally additional auxiliaries and additives.